In recent years, industrial enhancement and great product differentiation have brought about a great deal of variation in product design. Color diversification and transparent designs have attracted considerable attention. Variation in designs requires variation in raw materials. As a result, a great deal of research into transparent materials is actively underway.
For this reason, techniques for imparting transparency by incorporating acrylic acid alkyl ester or methacrylic acid alkyl ester monomers into an acrylonitrile-butadiene-styrene (ABS) resin that exhibits superior impact resistance, chemical resistance, processability and the like have been developed.
For example, Korean Patent No. 0360987 or 0423873 discloses a transparent resin obtained by graft-copolymerizing methyl methacrylate-styrene-acrylonitrile with a conjugated diene rubber. With respect to such a transparent resin, in order to avoid haze during processing, the methyl methacrylate-styrene-acrylonitrile copolymer serving as a hard shell should surround the rubber well. When the hard shell, methyl methacrylate-styrene-acrylonitrile copolymer does not surround the rubber well, the shape of the rubber is deformed and the surface thereof becomes rough due to shear occurring during processing, thus causing occurrence of haze and deterioration in transparency.
This has negative effects on color, thus causing discoloration or formation of flow marks. As the transparent ABS market expands, products with considerably high impact strength are required. Accordingly, there is a need for development of products containing a high amount of rubber.
In addition, attempts to improve graft copolymers having rubber contents are actively underway from the viewpoint of preparation advantages in that the preparation process is efficient and preparation costs are reduced when graft copolymers having a high content of rubber are used.
However, approaches to increase the content of rubber in final products or increase the content of rubber in the preparation process disadvantageously do not surround the surface of rubber well, thus obtaining products with deteriorated transparency and poor color.